Use a temp dir for CONF.state_path
Use a temp dir for CONF.state_path

external_pids will defaults to $state_path(/var/lib/neutron)/external/pids
which isn't accessible when running unit tests so use a tempdir for
CONF.state_path. This bug arose when oslo.config 1.3.0 came out which
fixed bug #1282250 (I4324bda6f3de3cdf05f8eb3cf16052c04018dec8) and
caused this issue.

Change-Id: I253c5ea85c51eff94399da0b9462d10a9c509a0f
Closes-Bug: #1301027

wenhuizhang/neutron,adelina-t/neutron,aristanetworks/neutron,paninetworks/neutron,cloudbase/neutron,mattt416/neutron,virtualopensystems/neutron,javaos74/neutron,watonyweng/neutron,vveerava/Openstack,vivekanand1101/neutron,leeseuljeong/leeseulstack_neutron,noironetworks/neutron,virtualopensystems/neutron,jacknjzhou/neutron,waltBB/neutron_read,cloudbase/neutron-virtualbox,vveerava/Openstack,leeseuljeong/leeseulstack_neutron,JianyuWang/neutron,Stavitsky/neutron,projectcalico/calico-neutron,pnavarro/neutron,mandeepdhami/neutron,mahak/neutron,igor-toga/local-snat,yamahata/tacker,vbannai/neutron,alexandrucoman/vbox-neutron-agent,gopal1cloud/neutron,cloudbase/neutron-virtualbox,jumpojoy/neutron,skyddv/neutron,neoareslinux/neutron,eonpatapon/neutron,dims/neutron,NeCTAR-RC/neutron,suneeth51/neutron,rdo-management/neutron,CiscoSystems/neutron,JioCloud/neutron,CiscoSystems/neutron,mahak/neutron,neoareslinux/neutron,paninetworks/neutron,SmartInfrastructures/neutron,yamahata/tacker,shahbazn/neutron,glove747/liberty-neutron,chitr/neutron,bgxavier/neutron,cernops/neutron,silenci/neutron,gopal1cloud/neutron,cisco-openstack/neutron,virtualopensystems/neutron,asgard-lab/neutron,jerryz1982/neutron,wolverineav/neutron,yuewko/neutron,cisco-openstack/neutron,antonioUnina/neutron,rdo-management/neutron,pnavarro/neutron,JianyuWang/neutron,dims/neutron,Stavitsky/neutron,eayunstack/neutron,gkotton/neutron,chitr/neutron,leeseuljeong/leeseulstack_neutron,vveerava/Openstack,mahak/neutron,antonioUnina/neutron,Metaswitch/calico-neutron,wenhuizhang/neutron,miyakz1192/neutron,dhanunjaya/neutron,cernops/neutron,blueboxgroup/neutron,takeshineshiro/neutron,noironetworks/neutron,silenci/neutron,yanheven/neutron,mmnelemane/neutron,sasukeh/neutron,magic0704/neutron,apporc/neutron,alexandrucoman/vbox-neutron-agent,bigswitch/neutron,yanheven/neutron,bigswitch/neutron,mmnelemane/neutron,huntxu/neutron,MaximNevrov/neutron,redhat-openstack/neutron,javaos74/neutron,SmartInfrastructures/neutron,barnsnake351/neutron,takeshineshiro/neutron,blueboxgroup/neutron,huntxu/neutron,leeseulstack/openstack,vivekanand1101/neutron,vbannai/neutron,shahbazn/neutron,Metaswitch/calico-neutron,yamahata/tacker,igor-toga/local-snat,vbannai/neutron,yuewko/neutron,MaximNevrov/neutron,sebrandon1/neutron,leeseulstack/openstack,dhanunjaya/neutron,JioCloud/neutron,openstack/neutron,miyakz1192/neutron,watonyweng/neutron,wolverineav/neutron,jerryz1982/neutron,eayunstack/neutron,openstack/neutron,gkotton/neutron,barnsnake351/neutron,sasukeh/neutron,klmitch/neutron,bgxavier/neutron,redhat-openstack/neutron,adelina-t/neutron,sebrandon1/neutron,gkotton/neutron,infobloxopen/neutron,openstack/neutron,apporc/neutron,klmitch/neutron,SamYaple/neutron,SamYaple/neutron,magic0704/neutron,asgard-lab/neutron,jumpojoy/neutron,skyddv/neutron,mattt416/neutron,waltBB/neutron_read,cloudbase/neutron,projectcalico/calico-neutron,swdream/neutron,eonpatapon/neutron,NeCTAR-RC/neutron,glove747/liberty-neutron,blueboxgroup/neutron,suneeth51/neutron,aristanetworks/neutron,infobloxopen/neutron,swdream/neutron,leeseulstack/openstack,jacknjzhou/neutron,mandeepdhami/neutron,CiscoSystems/neutron